The present invention relates to a height adjustable crutch, and more particularly to a type of height adjustable crutch in which the structure is simpler and stronger than the conventional types that one finds today.
As is well known, the general type of crutch has a dead structure, the height of which can not be adjusted in response to the requirements of different users, so the makers have to prepare a number of sizes.
Referring to FIG. 1, U.S. Pat. No. 4,509,741 provides an improved type of crutch having a bow A comprised of a pair of hollow tubular vertical members which are angled downwardly toward each other with their lower extremities aligned in a uniformly spaced parallel relationship. A hollow tubular carrier B is disposed between and in abutment with these tubular extremities and the three members are secured by bolt C through them in the upper area where they are in abutment and by an integral encircling element D at their lower extremities which is annexed to the lower extremities of the tubular members of the bow A by pins D1, D2. The tubular carrier B is orificed at selective intervals and receives an orificed telescoping foot member E provided with one outwardly radial spring F biased detent G, as shown in FIG. 2, which is an enlarged fragmentary sectional view of FIG. 1. This detent G serves to lock the foot member E in any disposition relative to the tubular carrier B when the detent G is passed through any registering orifices of the tubular carrier B and foot member E. The disposition of the foot member E relative to the tubular carrier B may be changed by passing the detent G radially inwardly to where the foot member E may then be moved upwardly or downwardly in relation to the tubular carrier B for redisposition and locking by the detent G.
However, as the strength of the structure between the tubular extremities of the bow A and the tubular carrier B of such a height adjustable crutch is dependent only on bolt C and pins D1, D2, it is not either durable or strong enough to be used for a long time without looseness or breakage. The minimum height of the crutch especially is limited by the position of the bolt C which is disposed radially through the tubular carrier B and blocks the top end of the same, so the adjustable range of the crutch is limited by the length of the tubular carrier B. As the crutch is adjusted in a relatively higher condition, the top end of the foot member E will be disposed near to the lower extremity of the tubular carrier B, so the stress generated by the foot member E will center on the pins D1, D2. For this reason, the encircling element D shall be loosened or broken sooner or later.